lib/envelope.c

   1 /********************************************************************
   2  *                                                                  *
   3  * THIS FILE IS PART OF THE OggVorbis SOFTWARE CODEC SOURCE CODE.   *
   4  * USE, DISTRIBUTION AND REPRODUCTION OF THIS SOURCE IS GOVERNED BY *
   5  * THE GNU LESSER/LIBRARY PUBLIC LICENSE, WHICH IS INCLUDED WITH    *
   6  * THIS SOURCE. PLEASE READ THESE TERMS BEFORE DISTRIBUTING.        *
   7  *                                                                  *
   8  * THE OggVorbis SOURCE CODE IS (C) COPYRIGHT 1994-2001             *
   9  * by the XIPHOPHORUS Company http://www.xiph.org/                  *
  10  *                                                                  *
  11  ********************************************************************
  12
  13  function: PCM data envelope analysis and manipulation
  14  last mod: $Id: envelope.c,v 1.31 2001/02/02 03:51:56 xiphmont Exp $
  15
  16  Preecho calculation.
  17
  18  ********************************************************************/
  19
  20 #include <stdlib.h>
  21 #include <string.h>
  22 #include <stdio.h>
  23 #include <math.h>
  24 #include <ogg/ogg.h>
  25 #include "vorbis/codec.h"
  26 #include "codec_internal.h"
  27
  28 #include "os.h"
  29 #include "scales.h"
  30 #include "envelope.h"
  31 #include "misc.h"
  32
  33 /* Digital filter designed by mkfilter/mkshape/gencode A.J. Fisher
  34    Command line: /www/usr/fisher/helpers/mkfilter -Ch \
  35    -6.0000000000e+00 -Bp -o 5 -a 1.3605442177e-01 3.1746031746e-01 -l */
  36
  37 #if 0
  38 static int    cheb_bandpass_stages=10;
  39 static float cheb_bandpass_gain=5.589612458e+01f;
  40 static float cheb_bandpass_B[]={-1.f,0.f,5.f,0.f,-10.f,0.f,
  41                                 10.f,0.f,-5.f,0.f,1f};
  42 static float cheb_bandpass_A[]={
  43   -0.1917409386f,
  44   0.0078657069f,
  45   -0.7126903444f,
  46   0.0266343467f,
  47   -1.4047174730f,
  48   0.0466964232f,
  49   -1.9032773429f,
  50   0.0451493360f,
  51   -1.4471447397f,
  52   0.0303413711f};
  53 #endif
  54
  55 /* 4kHz Chebyshev highpass */
  56 static int    cheb_highpass_stages=10;
  57 static float cheb_highpass_gain= 1.314337427e+01f;
  58 /* z^-stage, z^-stage+1... */
  59 static float cheb_highpass_B[]={1.f,-10.f,45.f,-120.f,210.f,
  60                                 -252.f,210.f,-120.f,45.f,-10.f,1.f};
  61 static float cheb_highpass_A[]={
  62   -0.1013448254f,
  63   0.4524819695f,
  64   -1.3268091670f,
  65   3.2875726855f,
  66   -7.2782468961f,
  67   13.0298867474f,
  68   -17.6698599469f,
  69   17.2757670409f,
  70   -11.6207967046f,
  71   4.8672119675f};
  72
  73 #if 0
  74 /* 6kHz Chebyshev highpass */
  75 static int    cheb_highpass_stages=10;
  76 static float cheb_highpass_gain= 5.291963434e+01f;
  77 /* z^-stage, z^-stage+1... */
  78 static float cheb_highpass_B[]={1.f,-10.f,45.f,-120.f,210.f,
  79                                 -252.f,210.f,-120.f,45.f,-10.f,1.f};
  80 static float cheb_highpass_A[]={
  81   -0.1247628029f,
  82   0.1334086523f,
  83   -0.3997715614f,
  84   0.3213011089f,
  85   -1.1131924119f,
  86   1.7692446626f,
  87   -3.6241199038f,
  88   4.1950871291f,
  89   -4.2771757867f,
  90   2.3920318913f};
  91 #endif
  92
  93 void _ve_envelope_init(envelope_lookup *e,vorbis_info *vi){
  94   codec_setup_info *ci=vi->codec_setup;
  95   int ch=vi->channels;
  96   int window=ci->envelopesa;
  97   int i;
  98   e->winlength=window;
  99   e->minenergy=fromdB(ci->preecho_minenergy);
 100   e->iir=_ogg_calloc(ch,sizeof(IIR_state));
 101   e->filtered=_ogg_calloc(ch,sizeof(float *));
 102   e->ch=ch;
 103   e->storage=128;
 104   for(i=0;i<ch;i++){
 105     IIR_init(e->iir+i,cheb_highpass_stages,cheb_highpass_gain,
 106              cheb_highpass_A,cheb_highpass_B);
 107     e->filtered[i]=_ogg_calloc(e->storage,sizeof(float));
 108   }
 109
 110   drft_init(&e->drft,window);
 111   e->window=_ogg_malloc(e->winlength*sizeof(float));
 112   /* We just use a straight sin(x) window for this */
 113   for(i=0;i<e->winlength;i++)
 114     e->window[i]=sin((i+.5)/e->winlength*M_PI);
 115 }
 116
 117 void _ve_envelope_clear(envelope_lookup *e){
 118   int i;
 119   for(i=0;i<e->ch;i++){
 120     IIR_clear((e->iir+i));
 121     _ogg_free(e->filtered[i]);
 122   }
 123   drft_clear(&e->drft);
 124   _ogg_free(e->window);
 125   _ogg_free(e->filtered);
 126   _ogg_free(e->iir);
 127   memset(e,0,sizeof(envelope_lookup));
 128 }
 129
 130 /* straight threshhold based until we find something that works better
 131    and isn't patented */
 132 static float _ve_deltai(envelope_lookup *ve,float *pre,float *post){
 133   long n=ve->winlength;
 134
 135   long i;
 136
 137   /* we want to have a 'minimum bar' for energy, else we're just
 138      basing blocks on quantization noise that outweighs the signal
 139      itself (for low power signals) */
 140
 141   float min=ve->minenergy;
 142   float A=min*min*n;
 143   float B=A;
 144
 145   /*_analysis_output("A",granulepos,pre,n,0,0);
 146     _analysis_output("B",granulepos,post,n,0,0);*/
 147
 148   for(i=0;i<n;i++){
 149     A+=pre[i]*pre[i];
 150     B+=post[i]*post[i];
 151   }
 152
 153   A=todB(A);
 154   B=todB(B);
 155
 156   return(B-A);
 157 }
 158
 159 static float _ve_ampi(envelope_lookup *ve,float *pre){
 160   long n=ve->winlength;
 161
 162   long i;
 163
 164   /* we want to have a 'minimum bar' for energy, else we're just
 165      basing blocks on quantization noise that outweighs the signal
 166      itself (for low power signals) */
 167
 168   float min=ve->minenergy;
 169   float A=min*min*n;
 170
 171   for(i=0;i<n;i++){
 172     A+=pre[i]*pre[i];
 173   }
 174
 175   A=todB(A);
 176   return(A);
 177 }
 178
 179 long _ve_envelope_search(vorbis_dsp_state *v,long searchpoint){
 180   vorbis_info *vi=v->vi;
 181   codec_setup_info *ci=vi->codec_setup;
 182   envelope_lookup *ve=((backend_lookup_state *)(v->backend_state))->ve;
 183   long i,j,k;
 184   float *work=alloca(sizeof(float)*ve->winlength*2);
 185
 186   /* make sure we have enough storage to match the PCM */
 187   if(v->pcm_storage>ve->storage){
 188     ve->storage=v->pcm_storage;
 189     for(i=0;i<ve->ch;i++)
 190       ve->filtered[i]=_ogg_realloc(ve->filtered[i],ve->storage*sizeof(float));
 191   }
 192
 193   /* catch up the highpass to match the pcm */
 194   for(i=0;i<ve->ch;i++){
 195     float *filtered=ve->filtered[i];
 196     float *pcm=v->pcm[i];
 197     IIR_state *iir=ve->iir+i;
 198     int flag=1;
 199
 200     for(j=ve->current;j<v->pcm_current;j++){
 201       filtered[j]=IIR_filter(iir,pcm[j]);
 202       if(pcm[j])flag=0;
 203     }
 204     if(flag && ve->current+64<v->pcm_current)IIR_reset(iir);
 205   }
 206
 207   ve->current=v->pcm_current;
 208
 209   /* Now search through our cached highpass data for breaking points */
 210   /* starting point */
 211   if(v->W)
 212     j=v->centerW+ci->blocksizes[1]/4-ci->blocksizes[0]/4;
 213   else
 214     j=v->centerW;
 215
 216   while(j+ve->winlength<=v->pcm_current){
 217     for(i=0;i<ve->ch;i++){
 218       float *filtered=ve->filtered[i]+j;
 219       float m=_ve_deltai(ve,filtered-ve->winlength,filtered);
 220
 221       if(m>ci->preecho_thresh){
 222         /*granulepos++;*/
 223         return(0);
 224       }
 225       if(m<ci->postecho_thresh){
 226         /*granulepos++;*/
 227         return(0);
 228       }
 229       /*granulepos++;*/
 230     }
 231
 232     /* look also for preecho in coupled channel pairs with the center
 233        subtracted out (A-B) */
 234     for(i=1;i<ve->ch;i+=2){
 235       float *filteredA=ve->filtered[i-1]+j-ve->winlength;
 236       float *filteredB=ve->filtered[i]+j-ve->winlength;
 237       float m;
 238
 239       for(k=0;k<ve->winlength*2;k++)
 240         work[k]=filteredA[k]-filteredB[k];
 241
 242       m=_ve_deltai(ve,work,work+ve->winlength);
 243
 244       if(m>ci->preecho_thresh){
 245         /*granulepos++;*/
 246         return(0);
 247       }
 248       if(m<ci->postecho_thresh){
 249         /*granulepos++;*/
 250         return(0);
 251       }
 252       /*granulepos++;*/
 253     }
 254
 255
 256     j+=min(ci->blocksizes[0],ve->winlength)/2;
 257
 258     if(j>=searchpoint){
 259       return(1);
 260     }
 261   }
 262
 263   return(-1);
 264 }
 265
 266 void _ve_envelope_shift(envelope_lookup *e,long shift){
 267   int i;
 268   for(i=0;i<e->ch;i++)
 269     memmove(e->filtered[i],e->filtered[i]+shift,(e->current-shift)*
 270             sizeof(float));
 271   e->current-=shift;
 272 }
 273
 274